As shown in FIG. 9, a known soy milk maker comprises an upper closed housing 11, a lower cup shaped housing 12 supporting the upper housing 11, and a motor 13 disposed inside the upper housing 11. The motor 13 comprises a rotor shaft 14 that extends into the lower housing 12. Blades 15 are fixed to the shaft 14 and rotate with the shaft 14. The upper housing 11 is detachable from the lower housing 12 for cleaning the blades 15. The bottom of the upper housing 11 comprises a seal structure 16 to avoid the motor 13 being affected by moisture from the lower housing 12.
However, the seal structure 16 affects the motor output. Also, the seal structure 16 will become worn over the time and the motor 13 will become affected by moisture.